A novel PLL control method for robust three-phase thyristor converter under sag and notch conditions

The paper presents a novel phase locked loop(PLL) control method for robust three-phase thyristor dual converters under sag, notch, and phase loss conditions. This method is applied to three line to line voltages of grid to derive three phase angle errors from three separated single-phase PLLs. They can substitute for abnormal phase to guarantee the synchronization in the various grid fault conditions. The performance of novel PLL with moving average method is verified through simulations.